Diodes with low dynamic resistance and low capacitance are useful in electronic circuits, for example in electrostatic discharge (ESD) protection circuits. Low capacitance is attained by a lightly doped layer of a forward-biased diode in series with a reverse-biased diode; the reverse-biased diode has a heavily doped buried layer over the substrate which sets the breakdown voltage. It is desirable to minimize the dynamic resistance and capacitance of the diode, while providing a desired breakdown voltage. In some applications, the desired breakdown voltage may be 6 volts to 8 volts; in other applications, the desired breakdown voltage may be significantly higher, for example in the range of 20 volts to 40 volts. The dynamic resistance is limited by the conductivity of the substrate; increasing the dopant density in the substrate to improve the dynamic resistance disadvantageously reduces the breakdown voltage. Simultaneously attaining desired values of dynamic resistance and breakdown voltage has been problematic.